I have an 86 250R. I have an opportunity to buy a brand new 88 motor. I know the 88 will bolt on fine since it's the same frame.

My question has to do wih everything else. what about my stock 86 carb? will that work fine or do I need to get the 88 carb?

Also, what changes were made in terms of power? I've never ridden an 88 and don't know what's different about the power delivery.

 

If you ha ve the chance to buy either motor...Buy the 88 motor i like the crankshaft better and the
transmission gears 5th gear is a better ratio.....

they are both about the same....everybody has there own opinion...

 

Are you sure it will fit. They changed the frame a bit in 88. The 86 motor has a shorter rod and a different piston. Here a some link to more in on the 250R Another

 

I think the '88 engine wont have the motor mount bolt holes that connect to the swingarm like the 86 has (well at least the 88 swingarm does not have the mounts, unless honda kept the cases the same even though they changed the swingarm). As for performance, the 88 engines ran smoother and revved higher. But it is said the 86s have more power.

 

you can put a 88 motor in a 86 bike and vice versa....
all parts inter-change (except 85 axle)
you will use a diff. motor mount on the rear of a 86 model